Abstract:

Between the years of 2006 and 2011, 183 marine mammal strandings were recorded and analyzed by the Veterinary Diagnostics Laboratory at Oregon State University. Most of the strandings were of pinnipeds and porpoises. The species represented were California sea lion (69 animals), Steller sea lion (18 animals), harbor seal (42 animals), northern elephant seal (11 animals), northern fur seal (3 animals), Guadalupe fur seal (2 animals), harbor porpoise (27 animals), Dall’s porpoise (1 animal), northern right whale dolphin (1 animal), common dolphin (2 animals), grey whale (2 animals), sperm whale (2 animals), minke whale (1 animal), and Cuvier’s beaked whale (2 animals). Most of the stranding events were of adults and sub-adults with fewer cases of neonates and yearlings. Necropsies were performed on 48 of the stranded animals at Oregon State University by Veterinary Pathologists, and 135 were on site by biologists. Most of the necropsies performed in the diagnostic laboratories were of pinnipeds while the on-site necropsies included the majority of the cetacean strandings. There was clear seasonality in the stranding events with most occurrences in the summer months (June-August) with a late spike of strandings in October. Important zoonotic diseases were confirmed in several of the stranded species. Leptospirosis was confirmed in 34 pinnipeds (California Sea Lion, Stellar Sea Lion, and Harbor Seal) with the majority of the deaths occurring in the years of 2009 and 2010. Encephalitis was found in 11 pinnipeds, 8 of which were seals with meningoencephalitis. Cryptococcosis, a disease known to afflict porpoises in British Columbia, was found in 4 porpoises (harbor porpoises and Dall’s Porpoise). Other notable causes of death were domoic acid toxicity, Clostridium infection, and Streptococcus infection. Other putative causes of mortality were toxoplasmosis in seals, and Otariid herpesvirus in Sea Lions. The high frequency of zoonotic disease found in animals off the Oregon Coast underscore the necessity for public education regarding the dangers of contact with stranded marine mammals.

Description:

Every year many marine mammals become stranded on the coast of the Pacific Northwest. The deaths of these animals are investigated and recorded by the North West Marine Mammal Stranding Network. Animals or tissues from animals, that are considered fresh enough for histopathology are brought for evaluation to the Veterinary Diagnostics Laboratory at Oregon State University. The diagnostic records detail the condition of the animal, disease status and cause of death. In this study, data will be collated from the diagnostic records at the Veterinary Diagnostics Laboratory (VisuaLab database) into an access database, incorporating information from the Marine Mammal Stranding Network as appropriate.
Over the last six years, a total of 183 cases have been accessioned into the Veterinary Diagnostics Laboratory database, involving sea lions, seals, porpoises, dolphins and whales. This data is accessible only via VisuaLab software, which provides limited support for data queries and is scheduled for retirement later this year, making subsequent access even more difficult. Converting this database into an access database will allow future synthesis with the Marine Mammal Stranding Network database and will ensure continued availability of all the data and provide an increased sample size for any future research.
Statistical analysis will be undertaken to ascertain the types, frequency, and distribution (e.g. species, age, gender, geography) of diseases and to look for trends in the cause of death marine mammals of the Pacific Northwest
The desired outcomes of this project are to obtain an increased knowledge and understanding of what research entails and how it is conducted, to contribute information regarding the health of marine mammal populations of the Pacific Northwest, and to create an accessible, user friendly database for other researchers in this field. Secondary desired outcomes of this project are to assist in marine mammal conservation efforts and to form the basis of future research projects allowing for in depth investigations of specific diseases and trends.